Removing and installing heater coolant shut-off valve, vehicles with 4-cyl. engine — AUDI

🧭 Before you start

Fits: Audi A4 B9 (8W, 2015–)

• Also covered elsewhere: Electronic parts catalogue

Don't miss

• Mark the positions of the coolant hoses (B, C, F) at N279(A).
• Depending on the version, provide support at the nuts (3) when screwing out the bolts (6).
• For noise insulation, the holder (H) is attached by way of the sleeves (E) and the rubber elements (D) (3x in each case).
• Check the installation position of N279(A), the holder (H) and all other components in this area (must not make contact with one another, noise).
• Residual coolant in the plenum chamber could result in an odour nuisance.

🔩 Torque settings

Values can differ between engine variants — check the code stamped on your block.

ℹ️ Always cross-check the exact figure against your vehicle's factory manual before final tightening — a wrong torque can damage the engine. These values are extracted from workshop data and may not cover every variant or revision.

📋 Procedure

1. Switch off the ignition (and auxiliary/supplementary heater).
2. ⚠ The cooling system is pressurised. When the engine is warm, the coolant temperature may be in excess of 90°C. Dissipate pressure and allow to cool down before performing repairs. Dissipate the pressure in the coolant circuit by opening the cap at the coolant expansion tank 19Cooling system/coolant; Draining and adding coolant — Dissipate the pressure in the coolant circuit by opening the cap on the coolant expansion tank.
3. Remove the plenum chamber cover General body repairs, exterior 50. Bulkhead; Removing and installing plenum chamber cover. [Note: The plenum chamber cover must be intact to stop water running into the heater and air conditioning unit via the intake housing with the plenum chamber cover fitted. The plenum chamber cover must also be properly and fully engaged in the windscreen frame General body repairs, exterior 50. Bulkhead; Removing and installing plenum chamber cover.]
4. Cover the area beneath the connections for the coolant hoses to the heater coolant shut-off valve N279(A) in the plenum chamber with absorbent paper for example. [Note: To stop coolant running into the plenum chamber on detaching the coolant hoses. Depending on the engine, vehicles with a 4-cyl. engine may be fitted with a non-return valve in the area of N279(A). The following illustrations show the arrangement on a vehicle with no non-return valve.]
5. Pinch off the coolant hoses (B, C, D, E) with hose clamps 3094 (or using commercially available pinch-off tools).

6. Mark the positions of the coolant hoses (B, C, F) at N279(A).
7. Unfasten the hose clamps (G) and detach the coolant hoses (B, C, F).
8. Unplug the connector (I).
9. Unscrew the nuts (B) (tightening torque 8 Nm) and detach N279(A). — 8 Nm (5.9 lb-ft)
10. Screw out the bolts (G) (tightening torque 5 Nm) and detach N279(A) (from the holder (H)). [Note: Depending on the version, provide support at the nuts (3) when screwing out the bolts (6).] — 5 Nm (3.7 lb-ft)
11. Check the cap (F) and the corresponding hose clamp for correct positioning.
12. N279(Fit A) (with holder (H)). [Note: For noise insulation, the holder (H) is attached by way of the sleeves (E) and the rubber elements (D) (3x in each case).]
13. ⚠ Pay attention to correct positioning of the coolant hoses at the shut-off valve. Interchanged coolant hoses could result in failure of the passenger compartment heating. — Butt-joint the coolant hoses (B, C, F) and secure at the marked locations with standard clamps. For clamp refer to Electronic parts catalogue.
14. Check the installation position of N279(A), the holder (H) and all other components in this area (must not make contact with one another, noise).
15. Check and if necessary clean the plenum chamber. [Note: Residual coolant in the plenum chamber could result in an odour nuisance.]
16. To bleed the coolant circuit, start the engine and actuate the circulation pump V55 and the heater coolant shut-off valve N279 with "“Guided fault-finding”" mode (see the separate procedure).
17. If applicable, check actuation and operation of the heater coolant shut-off valve N279"“Guided fault-finding”" mode.
18. Re-install the components removed in reverse order/re-attach the components unfastened.

Other AUDI procedures

• Removing and installing toothed belt – Audi · 56 torque figures
• Removing engine – Audi A8 D3 · 41 torque figures
• Removing camshaft timing chain from camshafts – Audi A6/A7 C7 · 38 torque figures
• Installing engine – Audi A8 D4 · 36 torque figures
• Removing and installing camshaft timing chain · 29 torque figures
• Removing and installing ceramic glow plugs – Audi · 2 torque figures
• Renewing timing chain cover (bottom)
• Removing and installing Bowden cable – Audi TT Mk2
• Removing and installing camshafts - cylinder head (left-side)
• Removing and installing turbocharger 1 control unit J724 - vehicles with 3.0 ltr. engine · 1 torque figures